Agitator filters/ Filter dryers



Filtering / Agitating

The solid/liquid mixture is introduced into the interior of the apparatus via a filler neck. Filtration is initiated with the help of a pressure difference above and beneath the filtration plate (pressure in upper part of filter housing, if necessary a vacuum at bottom of filter). The filter cake builds on the filter medium and this is smoothed down during the work phase by the lowering of the height-adjustable agitator. This closes any arising drying cracks and greatly improves the degree of dehumidification. Discharge of the solids begins with the counter rotation of the agitator. Through its further lowering, the filter cake is flaked off in layers with the angled scraper blades and is discharged through the discharge outlet on the side.

Advantages of our agitator filters/filter dryers

  • Uncomplicated automated loading
  • Processing within a closed system
  • Suitable for the processing of hazardous products and those harmful to health
  • Multiple intensive washing out of the filter cake with different washing fluids possible with low liquid consumption
  • Multiple intensive washing out of the filter cake with different washing fluids possible with low liquid consumption
  • Possibility of combining different procedure steps
  • Process automation through programmable plant control

The apparatus is constructed so that the following working procedures can be carried out:

  • Filtering
  • Agitating / Washing
  • Resuspending / Mixing
  • Extraction
  • Crystallising
  • Drying


The washing process serves the purpose of recovering the greatest amount of valuable filtrates or cleaning the filter cake of inherent impurities from previous reactions. A nozzle system evenly applies the wash fluid, which then rinses the solids once or several times as necessary. With the help of the agitator, the solids residue is intensively mixed with the wash fluid during the washing process. When the washing process is finished, the wash fluid is suctioned or squeezed off again and the cleaned solid is removed.


Extraction is the removal of individual components from a mixed substance using solvents, which can be done effectively by the agitator filter. The mixed substance is placed on the filter together with the solvent. Mixing with the agitator reduces the amount of solvent required and shortens the extraction times.


Crystallising in batches is another working process for which our agitator filters are suitable. This separation procedure is based on contact or vacuum cooling. With contact cooling, the heat exchange takes place via the hot/cold stores of the apparatus; with vacuum cooling the cooling process is implemented by heat removal by evaporation. In both cases additional agitation effects a better heat distribution, whereby the crystal particles can be held in an in-between state.


Because the interior of the filter forms a closed vacuum housing, the apparatus can be used for the drying of the filter cake once filtration is completed. Filter housing, filter base and if necessary even the agitator can be designed to be heated. The agitator beam then serves for continual shifting. The drying process can be accelerated by introducing warm air or pre-warmed inert gas through the filter cake.


Materials in contact with the product

For agitator filters, the material in contact with the product is usually stainless steel 1.4571. Depending on requirements, the filters can also be manufactured from stainless steel alloys or nickel alloys such as Hastelloy C 22.

Requirement profile

Depending on intended purpose, the machinery can be provided as a standard chemistry version or also in food-standards (FDA) and/or pharmaceutical-standards (GMP) versions. The ATEX version is selected to meet the prevailing zone ratings.

Construction sizes

We construct agitator filters in all current sizes from laboratory filters with a filtration area of only 0.15 m² to large apparatus with over 8 m² of usable filtration area.

Scope of delivery/ Package Unit

To meet customer requirements, the required peripherals of the apparatus, such as vacuum pump stands, solvent condensers, tempering systems or process controllers can be supplied.

Technical Centre

Laboratory trials are usually essential for the procedural design of dryers and filters. Our Technical Centre is equipped with a wide variety of technology for this purpose. Our equipment is also portable to enable our customers to carry out substance-based investigations in their factory.

Find out more about our Technical Centre here:    THE DVA TECHNICAL CENTRE